The broad objective of this research is to understand how the nervous system learns to produce postural activity that is optimally tuned for a given goal-directed movement. The proposed studies focus on anticipatory postural activity, which is a measure of how well the nervous system predicts the postural dynamics that will ensue as a movement is performed. Specific Aim 1 investigates the time course and tuning of anticipatory postural adjustments that occur when adults who are standing learn to reach in a novel, viscous force field. We will investigate whether the newly learned postural organization is stored by determining whether after-effects occur in anticipatory postural activity. Specific Aim 2 investigates whether anticipatory postural activity that has been tuned for reaching in a novel force field in one posture transfers to performance of the reaching task in another posture. We will study transfer between sitting and standing postures. Last, Aim 3 will investigate how the adaptive capacity of anticipatory postural adjustments differs between children and adults. This study will contribute to understanding of how postural control is optimized for movement and to devising rehabilitation strategies for individuals with posture control disorders.